Rafael Nadal believes Andy Murray's first grand slam title, achieved at the recent US Open, is not only a sign of more to come but also of the Brit's greater maturity.

Nadal is currently out of action with a knee injury, which forced his withdrawal from the US Open, and he had to watch on as Murray claimed his maiden major with victory over Novak Djokovic at Flushing Meadows.

"I think everybody knew he would win a grand slam, he's worked hard and has been pushing hard for many years at the top and he has achieved a reward for that," 11-time grand slam winner Nadal told ESPN of Murray's achievement.

Murray is currently attempting to defend his Japan Open title, which he won when beating Nadal in the final last year. He beat Lukas Lacko to reach the quarter-finals on Wednesday and will face Stanislas Wawrinka in the last eight.

Nadal heralded the Scot's tougher mental approach and improved consistency, both aspects that had been questioned prior to his US success. The Spaniard also praised Murray's all-round game which Nadal says makes him such a hard opponent to face.

"Andy's a very complete player all round. It's hard for me to speak about any specific area of his game which is particularly hard to face. He basically has it all, a great serve, backhand, forehand, he's fast, and he's a fantastic player all round.

"In recent years he's become a bit more consistent which is something you find with time, and he's one of the best in the world."

Nadal has been using his time away from tennis to develop a competitive edge in a different type of battle, by enhancing his poker skills. Known across the globe for his powers of focus and concentration, Nadal admits his current standard when it comes to cards is less than exemplary.

"My team is helping me improve a lot because my poker game is, well, let's say it's normal!" he laughed. "I like it, it's very competitive, it's a sport that's very different to the one I'm used to and that's something I enjoy. It's a game that can change in an instant, one which relies on a combination of skill and luck.

"Concentration is something that's been crucial throughout my career and it's something I can apply to playing poker, and I think you can apply that aspect across all games which are competitive."

Rafa Nadal was launching PokerStars' Rafa Dream Day promotion where fans can win the chance to meet, play tennis and compete against the sporting legend in an intimate poker game in Majorca. For details visit www.pokerstars.com